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34 
35 #ifndef INCLUDED_IMF_THREADING_H
36 #define INCLUDED_IMF_THREADING_H
37 
38 //-----------------------------------------------------------------------------
39 //
40 //	Threading support for the IlmImf library
41 //
42 //	The IlmImf library uses threads to perform reading and writing
43 //	of OpenEXR files in parallel.  The thread that calls the library
44 //	always performs the actual file IO (this is usually the main
45 //	application thread) whereas a several worker threads perform
46 //	data compression and decompression.  The number of worker
47 //	threads can be any non-negative value (a value of zero reverts
48 //	to single-threaded operation).  As long as there is at least
49 //	one worker thread, file IO and compression can potentially be
50 //	done concurrently through pinelining.  If there are two or more
51 //	worker threads, then pipelining as well as concurrent compression
52 //	of multiple blocks can be performed.
53 //
54 //	Threading in the Imf library is controllable at two granularities:
55 //
56 //	* The functions in this file query and control the total number
57 //	  of worker threads, which will be created globally for the whole
58 //	  library.  Regardless of how many input or output files are
59 //	  opened simultaneously, the library will use at most this number
60 //	  of worker threads to perform all work.  The default number of
61 //	  global worker threads is zero (i.e. single-threaded operation;
62 //	  everything happens in the thread that calls the library).
63 //
64 //	* Furthermore, it is possible to set the number of threads that
65 //	  each input or output file should keep busy.  This number can
66 //	  be explicitly set for each file.  The default behavior is for
67 //	  each file to try to occupy all worker threads in the library's
68 //	  thread pool.
69 //
70 //-----------------------------------------------------------------------------
71 
72 namespace Imf {
73 
74 
75 //-----------------------------------------------------------------------------
76 // Return the number of Imf-global worker threads used for parallel
77 // compression and decompression of OpenEXR files.
78 //-----------------------------------------------------------------------------
79 
80 int     globalThreadCount ();
81 
82 
83 //-----------------------------------------------------------------------------
84 // Change the number of Imf-global worker threads
85 //-----------------------------------------------------------------------------
86 
87 void    setGlobalThreadCount (int count);
88 
89 
90 } // namespace Imf
91 
92 #endif
93